Near-eye display (NED) devices such as head-mounted display (HMD) devices have been introduced into the consumer marketplace recently to support visualization technologies such as augmented reality (AR) and virtual reality (VR). A near-eye display device may include components such as one or more light sources, microdisplay modules, controlling electronics, and various optics such as waveguides, lenses, beam splitters, etc.
Waveguides may be used in a near-eye display device to convey light representing artificially-generated images from the image generation components of the device to an optical receptor of a user (e.g., a human eye). One or more of these waveguides may act as the device's image output interface to the user; these waveguides can be referred to as “output waveguides” of the device. For example, with a near-eye AR device, the user may see computer-generated images projected from a transparent output waveguide while the user views the real world through the output waveguide. In this way, the computer-generated images appear to be superimposed over the user's real-world environment.
Some waveguides in a near-eye display device may include diffraction optical elements in different regions that expand light wave signals in two dimensions. However, the choices of orientations and periods of the diffraction optical elements are limited in order to out-couple the expanded light wave signals in a desired direction.